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    <script>
        // 定义常量
        const PI = "3.14";
        console.log(PI);


        //----------------错误示范-------------------
        // 常量无法改变
        // PI = 3; // Assignment to constant variable.
        
        // 常量定义后必须赋值
        // const A; // Missing initializer in const declaration


    </script>
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